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biomechatronics: Lecture 3
 

biomechatronics: Lecture 3

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    biomechatronics: Lecture 3 biomechatronics: Lecture 3 Presentation Transcript

    • BiomechatronicsBart Koopmanlower extremity orthotics and prosthetics
    • Biomechatronics Artificial Sensors: artificial Controller: Actuator: Plant: artificial motor Orthosis Prosthesis Plant: Controller: Actuator: Skeletalintention CNS muscles system, external load Sensors: physiological sensory Physiological system
    • Prosthetics and Orthotics Prosthesis: • Replacement of body parts and/or functions Orthosis: • Support of body functions
    • Short history: amputation and prosthesiology• 1000 bC: Rig-Veda (sanskriet)• 400 bC: Hippocrates• 300 bC: eldest prosthesis
    • Amputation in middle agesH. Von Gerßdorf, 1517,Feldtbuch der Wundarztney
    • ArmprosthesisGötz von Berlichingen, Landshut1504
    • Ambroise Paré (1510-1590)
    • Prosthesis of Paré
    • Dominique Jean Larrey (1766-1843)
    • Modernamputationtechniques
    • OrthoticsFunctions:• Support• Redressing• Stabilization (immobilization)• Cosmetic
    • Control orthosis Controller: Activ- Plant:intention Central ation Actuator: force Skeletal Movement Nervous muscle system, system (CNS) external load Orthosis Sensors: physiological sensory system
    • Muscle control10 4 10 6 47 3 Mj1,pass fibermotor unit morphology fiber r11 + Joint 1 fiber Segments modelmotor unit fiber r12Muscle 1 fiber fibermotor unit morphology fiber r2 + Joint 2 fibermotor unit fiber Mj2,passMuscle 2 fiber
    • Normal control Mj1,pass External loads Knee angle r11 + knee jointMuscle 1 r12 Mechanical properties Segments model Hip angleMuscle 2 r2 + Hip joint Mj2,pass Sensor dynamics
    • control orthosis Orthosis Mj1,pass External loads Knee angle r11 + Knee jointMuscle 1 r12 Mechanical properties Segments model Hip angleMuscle 2 r2 + Hip joint Mj2,pass
    • Art. Sensors Orthosis Art. Controller Motor ProsthesisExample Skeletal CNS Muscles system Phys. Sensors UTX-swing orthosis • Knee Ankle Foot Orthosis for paralyzed knee muscles • controller allows flexion during swing and locking during stance
    • Leg orthosesOld KAFO UTX-swing
    • ProstheticsFunctions:• Support• CosmeticTF-prosthesis:• modular• 1,5 – 4 kg• 3 – 30 k€
    • Amputations in NL
    • Amputation causes
    • Normal control Mj1,pass External loads Knee angle r11 + knee jointMuscle 1 r12 Mechanical properties Segments model Hip angleMuscle 2 r2 + Hip joint Mj2,pass Sensor dynamics
    • control prosthesis Prosthesis Knee angle External Mechanical loads properties Segments model Hip angleMuscle 2 r2 + Hip joint Mj2,pass Sensor dynamics
    • control prosthesis External loads Mechanical Knee angle properties ProsthesisHip torque Hip angle Segments model Sensor dynamics
    • Prostetic knee design 4-axial knee: • Improve local stability • Improve controllability • No actuation!
    • Inverted knee design Model predictions: • increased push-off time • increased velocityPosterior view
    • Regular vs. inverse knee regular 4-axial knee polar curve 0,00 0 5 10 15 20 25 30 35 -0,50 instable dM/dϕ -1,00 -1,50 -2,00Post. Ant. Knee Angle [deg] inverted knee 1,50 1,00 stable dM/dϕ 0,50 0,00 0 5 10 15 20 25 30 35 -0,50 Knee Angle [deg]
    • Experimental results
    • Art. Sensors Orthosis Art. Controller Motor ProsthesisExample Skeletal CNS Muscles system Phys. Sensors EMG-activated prostheses • lower extremities: controlled damping, no motor, artificial sensors • upper extremities: myo-electric arm prosthesis, motor, no artificial sensors
    • Art. Sensors Orthosis Art. Controller Motor ProsthesisExample Skeletal CNS Muscles system Phys. Sensors
    • Art. Sensors Orthosis Art. Controller Motor ProsthesisExample Skeletal CNS Muscles system Phys. Sensors Otto Bock C-leg
    • Prosthetic foot design passive mechanism: • damping 10 J • energy storing?? • No actuation!
    • Concepts of gait• Walking is: – preventing to fall – cyclical movement with left/right foot placements in front of the other supporting body weight• The purpose of bipedal walking is to maximize the double support time while maintaining the forward velocity.• Stability is maintained by balancing the trunk through coordinated actions of joints.
    • Double support phase
    • Stilt walkingPelvic tilt: ±35°
    • Stilt walking + feetPelvic tilt: ±15°
    • Stilt walking + feet + kneesPelvic tilt: ±0°
    • Normal walking(feet, knees, ankles, pelvic rotation) Pelvic tilt: free
    • Why is d.s. phase important ? slow walking• Largest ground right left total reaction forces 1,4• largest muscle forces reaction force [-] 1,2 1 0,8• almost all mechanical 0,6 0,4 work 0,2 0• stable position 0 20 40 60 time [% stride] 80 100 other phases are more or less ballistic Maximize double support time !
    • Prosthetic / orthotic gaitWalking without knee function would result in…• Reduced velocity• Reduced double support time• Reduced step length• Increased pelvic tilt
    • Balancing mechanism • direct ground reaction force (push against large mass of trunk) • trunk will rotate (a little) • requires coordinated joint actions
    • Balancing mechanism
    • Trunk movement in walking Fast walking Normal walking Walking with large steps